Hi Carol, go down to your local dog walks (without your dog) and ask around other dog owners to see if you can find a suitable trainer.
You really need someone who will do some back up work with you, so look for this, your dog needs to be introduced to dogs in a safe environment, where no dog is going to get hurt.

Some behaviourist do help you to resocialise your dog, however others will charge you a lot of money just to tell you your dog needs socialising, but you already know that.

Some dog trainers would also be able to help you, but others would not, again look for someone with experience in dealing with behavioural problems.